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| United States Patent |
5,543,216
|
|
Shiomi
, et al.
|
August 6, 1996
|
Acrylic composite fiber
Abstract
Provided is a wool-like acrylic composite fiber having excellent crimp
developability, dyeability and processability, which is characterized in
that the difference in the amount of sulfonate groups in the higher and
lower heat shrinkable fiber components constituting the fiber is defined
to fall within a particular range, that the amount of sulfonate groups in
the higher heat shrinkable fiber component is periodically varied within a
particular range in the axial direction of the fiber, and that the product
of the difference in the amount of sulfonate groups between the higher and
lower heat shrinkable fiber components and the ratio of the maximum
content of sulfonate groups in the higher heat shrinkable fiber component
to the minimum content of the same is defined to fall within a particular
range. The composite fiber has a natural hand near to that of natural wool
and, when commercially dyed, it has much reduced dyeing specks. The
invention can freely design various composite fibers each having a
different hand in accordance with the use and the object of fibrous
products to be made of such fibers.
| Inventors:
|
Shiomi; Yozo (Okayama, JP);
Wakitani; Mituru (Okayama, JP)
|
| Assignee:
|
Japan Exlan Company Limited (Osaka, JP)
|
| Appl. No.:
|
374853 |
| Filed:
|
January 19, 1995 |
Foreign Application Priority Data
| Current U.S. Class: |
428/373; 428/374; 428/394 |
| Intern'l Class: |
D02G 003/00 |
| Field of Search: |
428/373,374
|
References Cited
U.S. Patent Documents
| 3693204 | Jan., 1972 | Ohki et al. | 428/374.
|
| 3719738 | Mar., 1973 | Fujii | 264/171.
|
| 3802177 | Apr., 1974 | Sekiguchi et al. | 57/140.
|
| 3864447 | Feb., 1975 | Sekiguchi et al. | 264/168.
|
| 3868816 | Mar., 1975 | Saji et a. | 428/362.
|
| 3895165 | Jul., 1975 | Lohwasser et al. | 428/374.
|
| 4297412 | Oct., 1981 | Achard et al. | 428/374.
|
| 4347203 | Aug., 1982 | Mimura et al. | 428/374.
|
| 4377648 | Mar., 1983 | Menault et al. | 428/374.
|
| 5232647 | Aug., 1993 | Sampanis et al. | 264/168.
|
| 5252396 | Oct., 1992 | Fukui et al. | 428/374.
|
| Foreign Patent Documents |
| 57-128219 | Aug., 1982 | JP.
| |
| 192717 | Nov., 1984 | JP | 428/374.
|
Primary Examiner: Ryan; Patrick
Assistant Examiner: Gray; J. M.
Attorney, Agent or Firm: Wenderoth, Lind & Ponack
Claims
What we claim is:
1. In an acrylic composite fiber consisting of a higher heat shrinkable
acrylonitrile copolymer fiber component made of acrylonitrile and
comonomer copolymerizable therewith and a lower heat shrinkable
acrylonitrile copolymer fiber component made of acrylonitrile and same or
different comonomer copolymerizable therewith, said higher heat shrinkable
fiber component and lower heat shrinkable fiber component being bonded
together in a side by side relationship in the axial direction of the
fiber, and the amount of the comonomer in the higher heat shrinkable fiber
component being larger by from 1 to 10% by weight than the amount of the
comonomer in the lower heat shrinkable fiber component, the improvement
wherein the amount of sulfonate groups in said composite fiber is from 0.2
to 1.0% by weight, the amount of sulfonate groups in the higher heat
shrinkable fiber component is larger by from 0.2 to 1.0% by weight than
the amount of sulfonate groups in the lower heat shrinkable fiber
component, and the amount of sulfonate groups in the higher heat
shrinkable fiber component is varied from AmaX to Amin and back to Amax
over a periodic cycle of from 50 to 600 mm along the axial direction of
the fiber, while satisfying the ranges defined by the following formulae
(1) and (2):
1.2.ltoreq.(Amax/Amin).ltoreq.3 (1)
wherein Amax and Amin respectively represent the maximum value and the
minimum value of the amount in % by weight of sulfonate groups, over said
periodic cycle in the axial direction of the fiber, in the higher heat
shrinkable fiber component;
0.24.ltoreq.(A-B).times.(Amax/Amin).ltoreq.2.5 (2)
wherein A and B respectively represent the amount in % by weight of
sulfonate groups on average, in the axial direction of the fiber, in the
higher and lower heat shrinkable fiber components.
Description
FIELD OF THE INVENTION
The present invention relates to an improved wool-like acrylonitrile
composite fiber having excellent crimp developability and excellent
dyeability and processability and characterized in that its crimps
developed are varied in the axial direction of the fiber.
BACKGROUND OF THE INVENTION
Heretofore, acrylonitrile composite fibers have been produced industrially
as fibrous materials for clothes, carpets, etc., as having excellent crimp
characteristics, high bulkiness, excellent dyeability, etc. As one example
of producing them, there is known a method for producing side-by-side
acrylonitrile composite fibers comprising composite components bonded
together in a side by side relationship, in which a spinning dope
comprising at least two acrylonitrile copolymers dissolved therein and
differing in the content of sulfonate groups (water reversible
components), as the components for forming the composite fiber, is let to
a spinnerette for bicomponent spinning and spun therethrough (for example,
Japanese Patent Publication No. 35288/82).
The water reversibility as referred to herein means such a property of
reversible elongation due to swelling with water and shrinkage due to
drying.
However, since the water reversible components are arranged in a laminar
state throughout the fiber length in such a prior art, the crimps of the
fiber are formed uniformly, being different from those of fibers of
natural wool which are naturally varied in the axial direction of the
fiber. Therefore, the hand of conventional acrylonitrile composite fibers
is hard, being different from that of fibers of natural wool. The dyeing
speed of acrylonitrile fibers having water reversible crimpability is
accelerated with the enlargement of the water reversibility because of
their sulfonate groups, with the result that they are often dyed unevenly
to have dyeing specks in commercial dyeing in which, therefore, fibrous
products made of the fibers cannot be dyed satisfactorily although
conventional acrylonitrile fibers are generally dyed well.
We, the present inventors repeated our studies so as to overcome the
above-mentioned drawbacks in the prior art and, as a result, have achieved
the present invention.
SUMMARY OF THE INVENTION
Specifically, the object of the present invention is to provide an
acrylonitrile composite fiber which has crimp developability varying in
the axial direction of the fiber and therefore has voluminousness and a
natural hand near to that of fibers of natural wool and which has been
improved to have reduced dyeing specks in commercial dyeing.
The object of the present invention has been attained by an improved
acrylic composite fiber consisting of a higher heat shrinkable
acrylonitrile copolymer fiber component (hereinafter referred to as ANA,
as the case may be) made of acrylonitrile and comohomer (hereinafter
referred to as comonomer ) copolymerizable therewith and a lower heat
shrinkable acrylonitrile copolymer fiber component (hereinafter referred
to as ANB, as the case may be) made of acrylonitrile and comonomer
(hereinafter referred to as comonomer b) copolymerizable therewith, said
higher heat shrinkable fiber component and lower heat shrinkable fiber
component being bonded together in a side by side relationship in the
axial direction of the fiber, and the difference in the amount between
comonomers a and b being from 1 to 10% by weight, which is characterized
in that the amount of sulfonate groups in said composite fiber is from 0.2
to 1.0% by weight, that the amount of sulfonate groups in the higher heat
shrinkable fiber component having a larger amount of comonomers
copolymerized is larger by from 0.2 to 1.0% by weight than the amount of
sulfonate groups in the lower heat shrinkable fiber component, and that
the amount of sulfonate groups in the higher heat shrinkable fiber
component is varied with a periodic cycle of from 50 to mm along the axial
direction of the fiber, while satisfying the range defined by the
following formulae (1) and (2):
1.2.ltoreq.(Amax/Amin).ltoreq.3 (1)
wherein Amax and Amin respectively represent the maximum value and the
minimum value of the amount (% by weight) of sulfonate groups, in the
axial direction of the fiber, in the higher heat shrinkable acrylonitrile
copolymer fiber component.
0.24.ltoreq.(A-B).times.(Ammax/Amin).ltoreq.2.5 (2)
wherein A and B respectively represent the amount (% by weight) of
sulfonate groups on average, in the axial direction of the fiber, in the
higher and lower heat shrinkable acrylonitrile copolymer fiber component.
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail hereunder. It is premised
that the difference in the amount between the comonomer a and the
comonomer b in the two acrylonitrile copolymer components ANA and ANB,
respectively, both constituting the acrylonitrile composite fiber of the
present invention is from 1 to 10% by weight. This is because, if the
difference in the copolymerizing ratio of the comonomers in these two
components is less than 1% by weight, the crimp developability of the
fiber due to the difference in the thermal shrinkage is low so that the
intended composite fiber cannot be obtained. When the difference in the
amount of sulfonate groups on average in these two components is made
large in order to elevate the crimp developability of the fiber, then the
amount of sulfonate groups to be the dyeing sites in the composite fiber
is thereby enlarged to accelerate the dyeing speed of the fiber with the
result that the fiber cannot be dyed satisfactorily although conventional
acrylonitrile fibers are generally dyed well. On the other hand, if the
difference in the copolymerizing ratio of the comonomers in these two
components is more than 10% by weight, the heat sensitivity of the fiber
is too large or, that is, the fiber is too much crimped due to the
difference in the thermal shrinkage based on the difference in the
acrylonitrile content between the two acrylonitrile copolymer components.
If so, it is impossible even by the technique of the present invention to
obtain the intended acrylonitrile composite fiber having a natural hand
near to that of fibers of natural wool.
The acrylonitrile copolymer for use in the present invention can be
obtained by aqueous suspension polymerization or the like which is well
known to be employable for acrylonitrile polymerization. As examples of
comonomer copolymerizable with acrylonitrile, mentioned are methyl
acrylate, vinyl acetate, methacrylic acid, etc.
These higher and lower heat shrinkable acrylonitrile copolymer fiber
components are bonded together in in a side by side relationship to give
the composite fiber of the present invention. The amounts of these
copolymers are such that the amount of the higher heat shrinkable
acrylonitrile copolymer fiber component is from 20 to 80% by weight and
that of the lower heat shrinkable acrylonitrile copolymer fiber component
is from 20 to 80% by weight.
If the amount of sulfonate groups to be the dyeing sites in the composite
fiber of the present invention is enlarged too much, the dyeing speed of
the fiber is accelerated too high so that the composite fiber cannot have
good dyeability, as so mentioned hereinabove. For this reason, the amount
of sulfonate groups in the composite fiber must be from 0.2 to 1.0% by
weight. This range shall apply to both the higher and lower heat
shrinkable acrylonitrile copolymer fiber components. If the amount of
sulfonate groups in question is less than 0.2% by weight, the
acrylonitrile composite fiber cannot have good dyeability. If, on the
other hand, it is more than 1.0% by weight, the dyeing speed of the fiber
is accelerated too high for the same reason as that mentioned hereinabove,
resulting in dyeing specks, etc. which noticeably detract from the quality
of the acrylonitrile fiber. If so, the object of the present invention
cannot be attained.
The higher heat shrinkable fiber component (ANA) as referred to herein
means an acrylonitrile copolymer fiber component having a larger content
of comonomer In addition, the amount of sulfonate groups in said higher
heat shrinkable fiber component (ANA) is larger than that of sulfonate
groups in the other lower heat shrinkable fiber component (ANB) while the
difference between the two amounts must be from 0.2 to 1.0% by weight.
This because, if the difference in the amount of sulfonate groups on
average, in the axial direction of the composite fiber of the present
invention, between the higher heat shrinkable fiber component and the
lower heat shrinkable fiber component is more than 1.0% by weight, the
dyeing speed of the fiber is too high, resulting in dyeing specks in
commercial dyeing of the fiber, and such dyeing specks noticeably detract
from the quality of the acrylonitrile fiber. On the other hand, if said
difference is less than 0.2% by weight, the water reversible crimpability
of the fiber or, that is, the crimp developability thereof based on its
water reversibility is lowered with the result that fibrous products
having a voluminous hand cannot be produced from the fiber. After such
fibers have once lost their voluminousness, it is extremely difficult to
restore them. Therefore, such composite fibers having such problems have
no value as commercial products.
The amount of sulfonate groups on average in the axial direction of the
fiber as referred to herein means the average of the amounts of sulfonate
groups in the two fiber components, one being the higher heat shrinkable
fiber component and the other being the lower heat shrinkable fiber
component. In the former higher heat shrinkable fiber component, the
amount of sulfonate groups shall be the sum of sulfonate groups in the
acrylonitrile copolymer and sulfonate groups from a polymer substance to
be added to the component later on.
The most characteristic aspect of the acrylonitrile composite fiber of the
present invention is that the amount of sulfonate groups in the higher
heat shrinkable fiber component constituting the fiber is varied with a
periodic cycle of from 50 to 600 mm along the axial direction of the
fiber, while satisfying the range defined by Formulae (1) and (2).
Since the amount of sulfonate groups in the higher heat shrinkable fiber
component is varied along the axial direction of the fiber, the parts of
the fiber having a higher content of sulfonate groups have high
crimpability, while making the entire composite fiber bulky and voluminous
because of the same effect as that to be attained when a small amount of
high shrinkable fibers are added to bulky yarns. Therefore, as compared
with a composite fiber containing therein the same amount of sulfonate
groups on average that have been uniformly arranged in laminar state, the
composite fiber of the present invention can be formed into fibrous
products having higher bulkiness and higher voluminousness.
Accordingly, to obtain fibrous products having bulkiness and voluminousness
on the same level from these fibers, the composite fiber of the present
invention may contain a smaller amount of sulfonate groups on average than
the composite fiber containing therein sulfonate groups that have been
uniformly arranged in laminar state. Therefore, the defect of dyeing
specks is relieved in commercial dyeing of fibrous products made of the
composite fiber of the present invention. On the other hand, it is
considered that the soft and voluminous hand of natural wool is considered
because of the gentle distribution of the crimps in the axial direction of
the fibers constituting it. According to the present invention, such a
soft and voluminous hand of the composite fiber of the invention has been
realized by the means mentioned below.
First, the object of the present invention has been attained by varying the
amount of sulfonate groups in the higher heat shrinkable fiber component
constituting the composite fiber of the invention in the axial direction
of the fiber while satisfying the range defined by Formulae (1) and (2).
In addition, the characteristic aspect of the composite fiber to be
provided by the present invention is that various composite fibers each
having a different hand can be freely designed in accordance with the use
and the object of fibrous products made of them by appropriately
controlling the degree of the variation in this amount.
However, if the product of the ratio (Amax./Amin.) of the maximum value
(Amax.) of the amount of sulfonate groups in the higher shrinkable fiber
component in the axial direction of the fiber to the minimum value (Amin.)
of the same and the difference (A-B) in the amount of sulfonate groups on
average between the higher and lower heat shrinkable fiber components is
less than 0.24% by weight, the dry crimp developability of the fiber is
low. If so, therefore, the composite fiber cannot be voluminous as its
water reversibility is low. If, however, the product is more than 2.5% by
weight, the fiber is too much crimped, resulting in having an extremely
hard hand, and, in addition, the dyeing speed of the fiber is extremely
high. If so, therefore, the fiber cannot be dyed uniformly, resulting in
noticeably detracting from the quality of the acrylonitrile fiber.
According to the present invention, the amount of sulfonate groups in the
higher shrinkable fiber component must be varied with a periodic cycle of
from 50 to 600 mm, preferably from 50 to 400 mm, along the axial direction
of the fiber. If the periodic cycle is lower than the lowermost limit, the
industrial producibility of such fibers is extremely poor. Therefore, such
is not employable. On the other hand, if the periodic cycle is higher than
the uppermost limit, the difference between the fiber and a composite
fiber containing therein sulfonate groups arranged in laminar state is
small, resulting in the decrease in the above-mentioned effect of the
present invention.
Where the acrylonitrile composite fiber of the present invention in which
the amount of sulfonate groups on average in the higher heat shrinkable
fiber component constituting the fiber is varied along the axial direction
of the fiber is produced by wet spinning in the presence of an inorganic
solvent, two acrylic polymers having different heat shrinkability, which
are produced by generally well-known aqueous suspension polymerization,
are separately dissolved to prepare spinning dopes. (The spinning dope
comprising the higher heat shrinkable acrylic polymer is referred to as
Ad; and the spinning dope comprising the lower heat shrinkable acrylic
polymer is as Bd.)
Next, a polymer substance that has been prepared separately by
copolymerizing monomers having sulfonate group is added to Ad while
changing with time the amount thereof to be added by changing the rotation
number of the measuring pump in the way of the pipe line for feeding the
spinning dope. Then, while these are continuously mixed and dissolved, the
resulting blend is led to a spinnerette for bicomponent spinning, along
with the other component Bd, and extruded into a coagulation bath. Then,
this is washed with water, stretched, dried for collapsing, wet-treated
under heat, treated with an oil agent, treated for crimp formation, etc.
After this process, a final fiber is formed. To change with time the
amount to be added, employable are a continuously changing method and a
stepwise changing method.
As examples of the monomers having sulfonate groups for acrylonitrile
polymers to be used in Ad and Bd or as the polymer substance, mentioned
are sodium methallylsulfonate, sodium styrene-parasulfonate, sodium
vinylsulfonate, sodium allylamidomethylpropane-sulfonate, and the
corresponding potassium salts. The amount of sulfonate group as referred
to herein is in terms of the amount of the corresponding sulfonic acid.
As one example of the polymer substance to be prepared by copolymerizing
monomers having sulfonate group, mentioned is a latex comprising
acrylonitrile/methyl acrylate/sodium styrene-parasulfonate monomers, Which
is obtained by copolymerizing these monomers by ordinary aqueous
continuous polymerization using a redox catalyst comprising ammonium
persulfite/sodium pyrosulfite. However, this is not limitative.
Next, the present invention will be described more concretely by means of
the following examples, in which the water reversibility, the crimp
characteristic, the dyeing rate and the other characteristics of the
fibers obtained are measured by the methods mentioned below.
(1) Percentage of water reversibility (%):
This is calculated by the following formula:
[(L.sub.W -L.sub.D)/(L.sub.1 -L.sub.D)].times.100
wherein L.sub.1 represents the original length of the ply of the gray
fibers corresponding to about 300 d, as measured under a weight of 11 mg/d
applied thereto;
L.sub.w represents the length of the same ply sample, as measured in such a
way that it is first boiled in water, while being kept free therein, for
15 minutes and then cooled at 20.degree. C. or lower, and, after water is
removed therefrom with a filter paper, a weight of 11 mg/d is applied
thereto; LB represents the length of the same ply sample, as measured in
such a way that the wet sample mentioned above is then dried at 80.degree.
C. for 30 minutes, while being kept free, and cooled to room temperature,
and a weight of 11 mg/d is applied thereto.
(2) Crimp characteristic: (n=50), JIS L1015
Cn: number of crimps (/25 mm) coefficient of variation (%)=(standard
deviation/average value).times.100
Ci: percentage of crimps (%) coefficient of variation (%)=(standard
deviation/average value).times.100
(3) Dyeing speed (dyeing rate):
dye bath (master solution): 3.5% of dye (Sumiacryl Orange 3R), 3.0% of
acetic acid
liquor ratio: 1/100
temperature, time: 93.degree. C..times.60 min.
measurement: colorimetric method for the residual dye solution after
dyeing, using a spectrophotometer (470 m.mu.)
##EQU1##
(4) Bulkiness of knit fabric: sample: 5G.times.2P Sheeting knit
fabric.times.4 layers
weight, measurement: The thickness (mm) of the knit fabric was measured
under a load of 0.1 g/cm.sup.2 applied thereto.
(5) Compressibility:
machine used: Tensilon RTA-500
compression speed: 20 mm/min
compression area: 70 mm.sup.2
sample: 5G.times.2P sheeting knit fabric.times.4 layers
measurement: The thickness (mm) of the sample under a load of 0.1
g/cm.sup.2 is referred to as L1. The thickness (mm) of the sample under a
load of 10 g/cm.sup.2 is referred to as L2. Compressibility (%)
=[(L1-L2)/L1].times.100
In the following tables, the marks .largecircle., .DELTA. and .times.
indicate the results of the evaluation of the tested items, each having
the following meanings:
For level dyability;
.largecircle.: The sample tested can be dyed satisfactorily in commercial
dyeing.
.DELTA.: The sample tested is dyed somewhat unevenly to have dyeing specks
in commercial dyeing, but this can be put to practical use, if limited.
.times.: The sample tested is dyed unevenly to have dyeing specks, which
noticeably detract from the outward appearance and the quality of the dyed
sample.
For handling of knit fabric;
.largecircle.: The sample satisfies the object of the present invention, as
having a good hand similar to that of natural wool.
.DELTA.: The sample has somewhat poor voluminousness, and its handling is
somewhat harsh to the touch.
.times.: The sample has poor voluminousness, and its
handling is harsh to the touch.
EXAMPLE 1
As the higher heat shrinkable fiber component (Ap component) of the
composite fiber to be prepared herein, used was a copolymer comprising 88%
by weight of acrylonitrile, 11.7% by weight of vinyl acetate, as the
second component and 0.3% by weight of sulfonate group and having [.eta.]
of 1.5. As the lower heat shrinkable fiber component (Bp component) of the
same, used was a copolymer comprising 90% by weight of acrylonitrile, 9.7%
by weight of methyl acrylate and 0.3% by weight of sulfonate group and
having [.eta.] of 1.5.
The two copolymers, Ap and Bp were separately dissolved in an aqueous
solution of 48% sodium rhodanate to prepare spinning dopes (Ad, Bd) having
a copolymer content of 11% by weight.
50% by weight of acrylonitrile, 30% by weight of methyl acrylate and 20% by
weight of a sulfonate group-containing monomer, sodium
styrene-parasulfonate were polymerized by continuous polymerization using
a redox catalyst comprising ammonium persulfite/sodium pyrosulfite, to
prepare a semi-permeable latex (C) containing 7.5% by weight of sulfonate
groups and having a dry solid content of 19% by weight.
The spinning dope of Bp component (Bd) was fed, directly as it was, into a
bicomponent spinning device, such as that described in Japanese Patent
Publication No. 24301/64, in such a way that the ratio of Ap/Bp might be
1/1. On the other hand, the spinning dope of Ap component (Ad) was fed
into an in-line mixer in which the dope fed thereinto could be stirred at
a high stirring rate, said mixer having been combined with the pipe line
of the device for feeding spinning dopes thereinto, while latex (C) that
had been prepared separately was also fed into said in-line mixer, added
to, mixed with and dissolved in dope (Ad) therein in such a way that the
proportions of sulfonate groups in the resulting blend might be those
shown in Table 1 below. Thus, mixed spinning dope (Al) was formed
continuously, which was then led into the bicomponent spinning device. To
lead latex (C) to the inline mixer, used was a gear pump having excellent
measurability.
Next, these Al and Bd dopes thus introduced into the bicomponent spinning
device were wet-spun into an aqueous solution of 10% sodium rhodanate at
0.degree. C., and the resulting wet filament was stretched 10 times in
boiling water and then dried in hot air at 115.degree. C. The thus
obtained fiber was then heat-treated in pressure steam at 113C to form a
composite fiber of 5 d. The thus-obtained composite fiber was thereafter
spun by an ordinary method to form a spun yarn with a metric count to
2/20's, which was then dyed by hank dyeing. The thus-dyed yarns were
knitted into a sheeting knit fabric of 5 gauge.times.2 ply. The
characteristics of the gray composite fibers and the knit fabrics thus
obtained are shown in Table 1 below.
TABLE 1
______________________________________
Sample No. 1 2 3 4 5
______________________________________
Amount of sulfonate groups (%)
A component 0.4 0.6 0.9 1.3 0.9
B component 0.3 0.3 0.3 0.3 0.3
1 A - B 0.1 0.3 0.6 1.0 0.6
2 Ratio of Amax./Amin.
1 2 2 2 1
1 .times. 2 0.1 0.6 1.2 2.0 0.6
Periodic cycle (mm) of Amax..about.
.infin.
200 200 200 .infin.
Amin.
Water reversibility (%)
5 26 41 72 38
Crimps after boiling, Cn (number
19 21 24 32 28
of crimps)
Coefficient of variation in Cn
9 12 13 15 10
(%)
Crimps after boiling, Ci (%)
28 35 36 40 36
Coefficient of variation in Ci (%)
11 25 31 41 13
Dyeing rate (%) 53 65 77 93 77
Uniform dyeability by dip dyeing
.largecircle.
.largecircle.
.largecircle.
.DELTA.
.largecircle.
Hand of knit fabric voluminous-
X/X .DELTA./.smallcircle.
.smallcircle./.smallcircle.
.smallcircle./.smallcircle.
.DELTA./X
ness/softness
Bulkiness (mm) 12 17 19 24 17
Compressibility 48 56 58 56 46
______________________________________
From the results in Table 1 above, it is known that samples Nos. 1 and 5
having a periodic cycle of Amax. .about. Amin of .infin. (these samples
are conventional composite fibers having therein sulfonate groups
uniformly arranged in laminar state) have low bulkiness or low
compressability and therefore have poor voluminousness and softness, while
samples Nos. 2 to 4 of the present invention all have a larger coefficient
of variation in crimps and therefore have larger bulkiness and
compressability to have a soft and voluminous hand similar to that of
natural wool than the conventional composite fibers having therein
sulfonate groups uniformly arranged in laminar state.
EXAMPLE 2
Composite fibers of 5d were formed in the same manner as in Example 1,
while varying the mixing ratio of the copolymer dopes and the latex to the
range shown in Table 2 below. The characteristics of the gray composite
fibers and the knit fabrics obtained are shown in Table 2.
TABLE 2
______________________________________
Sample No. 6 7 8 9 10 11
______________________________________
Amount of sulfonate
groups (%)
A component 0.6 0.6 0.9 1.2 1.0 1.2
B component 0.3 0.3 0.3 0.3 0.3 0.3
1 A - B 0.3 0.3 0.6 0.9 0.7 0.9
2 Ratio of Amax./Amin.
1.0 1.2 1.5 2.0 3.0 3.0
1 .times. 2 0.3 0.36 0.9 1.8 2.5 2.7
Periodic cycle (mm) of
.infin.
200 200 200 200 200
Amax..about.Amin.
Water reversibility (%)
22 24 38 66 41 69
Crimps after boiling, Cn
20 20 23 30 25 32
(number of crimps)
Coefficient of variation in
10 10 12 14 16 16
Cn (%)
Crimps after boiling, Ci
33 34 35 40 37 40
(%) 33
Coefficient of variation in
12 17 26 37 43 46
Ci (%)
Dyeing rate (%)
65 65 77 88 81 88
Uniform dyeability by dip
.smallcircle.
.smallcircle.
.smallcircle.
.DELTA. .times.
dyeing
Hand of knit fabric
.times./.times.
.DELTA./.DELTA.
.smallcircle./.smallcircle.
.smallcircle./.smallcircle.
.smallcircle./.smallcircle.
.smallcircle./.smallcircle.
voluminousness/softness
Bulkiness (mm) 13 14 18 23 21 23
Compressibility (%)
46 50 55 56 56 57
______________________________________
From the results shown in Table 2 above, it is known that the knit fabric
of sample No. 6 having a periodic cycle of Amax. .about. Amin. of being
.infin. has low bulkiness or low compressability and therefore has poor
voluminousness and softness and that the knit fabric of sample No. 11
having a value of 1.times.2 of being more than 2.5 is uneven and has
extremely bad appearance and quality to be unacceptable as a fibrous
product for commercial sale, whilst samples Nos. 7 to 10 have obviously
excellent voluminousness, softness and dyeability.
EXAMPLE 3
Composite fibers of 5d were formed in the same manner as in Example 1,
while varying the mixing ratio of the copolymer dopes and the latex to the
range shown in Table 3 below. The characteristics of the gray composite
fibers and the knit fabrics obtained are shown in Table 2.
TABLE 3
______________________________________
Sample No. 12 3 13 14 15
______________________________________
Amount of sulfonate groups
(%)
A component 0.9 0.9 0.9 0.9 0.9
B component 0.3 0.3 0.3 0.3 0.3
1 A - B 0.6 0.6 0.6 0.6 0.6
2 Ratio ofAmax./Amin.
2 2 2 2 2
1 .times. 2 1.2 1.2 1.2 1.2 1.2
Periodic cycle (mm) of Amax..about.
100 200 400 500 700
Amin.
Water reversibility (%)
42 41 40 39 38
Crimps after boiling, Cn
25 24 23 23 27
(number of crimps)
Coefficient of variation in
13 13 12 12 10
Cn (%)
Crimps after boiling, Ci
37 36 35 35 36
(%) 33
Coefficient of variation in
33 31 28 25 17
Ci (%)
Dyeing rate (%) 77 77 77 77 77
Uniform dyeability by dip
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dyeing
Hand of knit fabric
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voluminousness/softness
16
Bulkiness (mm) 20 19 18 18 16
Compressibility (%)
60 58 57 54 47
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From the results shown in Table 3 above, it is known that the coefficient
of variation in crimps becomes smaller with the increase in the periodic
cycle of Amax. .about. Amin., resulting in worsening the voluminousness
and the softness of the samples. Sample No. 15 having a periodic cycle of
700 mm cannot have the intended natural wool-like hand. On the other hand,
if the producibility is ignored, a sample having a periodic cycle of 40 mm
can be formed but this is unacceptable as a commercial product in view of
the industrial cost performance.
According to the-present invention, the difference in the amount of
sulfonate groups between the higher and lower heat shrinkable fiber
components constituting the composite fiber of the invention is defined to
fall within a particular range while the amount of sulfonate groups in the
higher heat shrinkable fiber component is varied with a periodic cycle
falling within a particular range, along the axial direction of the fiber,
by which the fiber is made to have a gentle variation in crimps in the
axial direction of the fiber. Accordingly, the composite fiber thus
provided by the present invention can have a natural wool-like hand.
However, a conventional composite fiber where the heat shrinkable fiber
component or the water reversible component is arranged in uniform laminar
state throughout the fiber length, that is produced by the prior art, has
a hard hand and cannot have a natural wool-like hand, since the crimps of
the fiber are uniform.
Since the amount of sulfonate groups in the higher heat shrinkable fiber
component constituting the composite fiber of the present invention is
periodically varied within a particular range, along the axial direction
of the fiber, the bulkiness and the voluminousness of the entire composite
fiber can be improved due to the higher crimpability of the parts of the
fiber having a larger amount of sulfonate groups, because of the same
effect as that to be attained when a small amount of high shrinkable
fibers are added to bulky yarns. Therefore, to obtain fibrous products
having bulkiness and voluminousness on the same level from these fibers,
the composite fiber of the present invention may contain a smaller amount
of sulfonate groups on average than the composite fiber containing therein
sulfonate groups that have been uniformly arranged in laminar state, with
the result that the defect of dyeing specks is relieved in commercial
dyeing of fibrous products made of the composite fiber of the present
invention.
In addition, by appropriately controlling the degree of the periodic
variation in the amount of sulfonate groups in the higher shrinkable fiber
component along the axial direction of the fiber, various composite fibers
each having a different hand can be freely designed in accordance with the
use and the object of fibrous products made of them. Such is one of
remarkable effects of the present invention.
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